1. Field of the Invention
The present invention relates to a mobile body that moves along a magnetic pole path in which a plurality of pairs of magnetic poles, each including a north pole and a south pole, are arranged, by using a linear motor. The present invention also relates to a mobile body system and a position detecting method for the mobile body.
2. Description of the Related Art
There has been generally known a mobile body system including a mobile body having a linear motor and a magnetic pole path in which a plurality of pairs of magnetic poles, each including a north pole and a south pole, are arranged. In the mobile body system, the linear motor is driven by a magnetic interaction with a magnetic flux of the magnetic pole path, and the mobile body thereby moves along the magnetic pole path.
In the mobile body system, a length of the magnetic pole path variously changes depending on a factory layout, for example, and hence it may be difficult to unify a pitch length of the magnetic pole path (a length of a pitch when a pair of magnetic poles is taken as one pitch) to a prescribed pitch length. In such a case, the magnetic pole path includes a section having a different pitch length from the prescribed pitch length, and thus includes a plurality of kinds of pitch lengths in a mixed state.
However, in the mobile body system, on the assumption that the pitch length of the magnetic pole path is made uniform to the prescribed pitch length, the mobile body detects a phase angle in accordance with the magnetic flux of the magnetic pole path by using a magnetic sensor and converts the phase angle to an actual position of the magnetic pole path. Therefore, when the magnetic pole path includes a plurality of kinds of pitch lengths in a mixed state, the mobile body is unable to detect the position of the mobile body with high accuracy in the section having a different pitch length from the prescribed pitch length.